1. Field of the Invention
The present invention relates to an image forming apparatus which receives printing information through a communication line, and performs printing based on the printing information.
2. Description of the Related Art
Generally, an image forming apparatus, such as a printer, a copier and a digital composite machine, using toner or ink as a printing material is know. Such an image forming apparatus requires a printing cost corresponding to the quantity of toner used for printing each image data included in the printing information, when toner is used for printing, for example. Therefore, the user demands for decreasing the cost by decreasing the quantity of toner. To realize this demand, it is considered to decrease the quantity of toner by performing image processing to decrease the image data printing area, and then printing based on this processed printing information.
However, the printing information, received by an image forming apparatus connected to a computer system via a network, includes different kinds of image data such as text data, graphic data and image data. Thus, it is possible to maintain the printing quality of the text data, while decreasing the quantity of toner by processing the image data to decrease the quantity of toner to meet the text data. But, for the image data, even if the toner quantity can be decreased, the printing quality may not be maintained because of the stripes (moirés) occurred on the printed image. There is a toner save mode to evenly decrease the quantity of toner, but the purpose of this mode is only to decrease the toner quantity, and the printing quality is not good.
Therefore, there is a need for an image forming apparatus which can decrease the quantity of printing material used for printing to meet the kinds of image data included in the received printing information, and maintain the printing quality, as well.